Add $ANDROID_BUILD_TOP to GDB source search paths

Without this change, GDB doesn't display the sources e.g. upon the
`list` command or when run with `--tui` option.

Test: art/test.py -v -j56 --host --64 --optimizing \
      --ndebuggable --gdb -t 071-dexfile-map-clean \
      --run-test
Test: art/test.py -v -j56 --host --64 --optimizing \
      --ndebuggable --gdb-dex2oat -t 071-dexfile-map-clean \
      --run-test
Change-Id: If7e43f3d0515333e5e9713f56cd62960e7e9a0c6
diff --git a/test/default_run.py b/test/default_run.py
index 6e334d0..c9dcb0a 100755
--- a/test/default_run.py
+++ b/test/default_run.py
@@ -653,7 +653,7 @@
       GDB = f"{GDBSERVER_DEVICE} --no-startup-with-shell 127.0.0.1{GDBSERVER_PORT}"
     else:
       GDB = "gdb"
-      GDB_ARGS += f" --args {DALVIKVM}"
+      GDB_ARGS += f" -d '{ANDROID_BUILD_TOP}' --args {DALVIKVM}"
 
   if INTERPRETER:
     INT_OPTS += " -Xint"
@@ -823,7 +823,8 @@
 
     if USE_GDB_DEX2OAT:
       nonlocal GDB_DEX2OAT_EXTRA_ARGS
-      dex2oat_cmdline += f"gdb {GDB_DEX2OAT_EXTRA_ARGS} --args "
+      dex2oat_cmdline += f"gdb {GDB_DEX2OAT_EXTRA_ARGS} \
+                          -d '{ANDROID_BUILD_TOP}' --args "
 
     dex2oat_cmdline += f"'{ANDROID_ART_BIN_DIR}/{dex2oat_binary}' \
                         {COMPILE_FLAGS} \